Carborane and derivatives of carborane belong to a class of compounds known to be effective ballistic modifiers for obtaining high burning rates. A number of derivatives of carborane also serve as effective plasticizers in composite propellants. n-Hexylcarborane (NHC) has been used in propellant, however, the low yield of the process for preparation and the complex process for preparation contribute to the high cost of n-hexylcarborane. Similarly, other alkyl carboranes have been prepared with corresponding results of high costs due to complexities of processes and the low yields (40%) thereof. Although extensive efforts have been spent toward improving the NHC process, no significant increases in yields have been achieved.
A simpler process than the NHC process is desired to produce derivatives of carborane in higher yield to result in lower cost than NHC or similar alkyl carboranes. The derivatives of carborane desired for propellant use must process compatibility, high yield and simple process of preparation, plasticizing effectiveness, high burning rates, and desirable properties to achieve good physical properties (stress/strain, etc.) of the propellant at high and low temperatures.
Therefore, the primary object of this invention is to provide propellant compositions which employ carboranylmethyl alkyl sulfides as effective plasticizers.
Another object of this invention is to provide high quality propellant compositions employing carboranylmethyl alkyl sulfides which contribute to good processing characteristics of the propellant.
A further object of this invention is to provide propellant compositions which yield high burning rates while employing carboranylmethyl alkyl sulfides.
An additional object of this invention is to provide propellant compositions which employ carboranylmethyl alkyl sulfides to yield improved mechanical properties of the propellants wherein used.